Originally Posted by Air Randy
You can go with 4" lift springs and you will hate yourself because of the lousy ride, both on and off road. If you do the SOA correctly (east to do it right) your rig will ride and handle better plus it will perform better off road.
Whether you do 4" lift or SOA you will have to rotate your rear pinion up due to the driveline angle and then have a dual cardan CV driveshaft built. Otherwise you will have vibration and be replacing rear U joints quite frequently. You will have to grind out the valleys on your front driveshaft yoke to keep it from binding and breaking at full droop unless you do a cut & turn on the front housing (the right way to do it).
IMHO either do a 2" lift and 33's or do a SOA if you want to go bigger.
Kevin, you should come drive my 40 for a day. Sprung under. 4" lift and 33" tires. Extended the back drive shaft but no double cardan CV needed. No grinding on the front shaft needed. Did not do a shackle reversal. Did put in some 4 degree shims in the front axle packs (cut and turn is better, as Randy says, but the shims work fine). Also, I have Saginaw PS, which is a great upgrade.